Jeb Bush has been talking on the campaign trail about a Colorado V.A. hospital whose construction cost, originally estimated at $600 million, soared to $1.7 billion. The Atlantic's CityLab site has an article reporting on an example of another amazing government construction cost overrun, the reconstruction of the San Francisco Bay Bridge. It started out at $250 million, and now could cost as much as $13 billion when interest and financing costs are included.
The article quotes a professor who wrote a book about the project: "Here you tell the public in '95: we can do the whole thing for $250 million. They vote on a bond measure that allows them to fund this plus other retrofits in the state. Then they come back and go, actually it's $1 billion."
The article also quotes an engineer suggesting that the initially misleadingly low cost estimates are a way to win approval of a project by misleading the electorate: "Basically at the onset of a project I think the higher ups prefer a dollar amount and schedule that doesn't shock the public."